Universal Mobile Telecommunications System (UMTS) is a third generation (3G) mobile communication system using a Wideband Code Division Multiple Access (WCDMA) air interface technology. With the development of 3G mobile communication systems, in order to adopt high-speed wireless access technologies such as Worldwide Interoperability for Microwave Access (WiMAX) in UMTS to maintain the vitality and competitiveness of the WCDMA/Global System for Mobile Communications (GSM) in 3GPP standards, the 3rd Generation Partnership Project (3GPP) proposed the UMTS Long Term Evolution (LTE), in which the physical layer is based on Orthogonal Frequency Division Multiple (OFDM) access technologies.
In the LTE physical layer, the system bandwidth may be 1.25 MHz, 1.6 MHz, 2.5 MHz, 5 MHz, 10 MHz, 15 MHz, or 20 MHz, and system resources are time-frequency resources. That is, the LTE physical layer includes two-dimensional resources in the time domain and frequency domain. In an LTE system, a sub-carrier occupies a bandwidth of 15 KHz, each frame is 10 ms long and consists of twenty time slots, each time slot contains seven OFDM symbols, and there are pilots in both the LTE uplink and downlink channels. For example, as shown in FIG. 1, the downlink pilots are located at the first and fifth OFDM symbols of each time slot in the time domain.
In a UMTS WCDMA system, in order to support the mobility of the system, the quality of a pilot signal needs to be measured. Likewise, for the LTE system, the quality of the pilot signal also needs to be measured.
Currently, a measurement model of a network side and a terminal side in a WCDMA system is as shown in FIG. 2.
In the model shown in FIG. 2:
A represents measurement sample data obtained through measurement in a physical layer;
Layer 1 filtering represents physical layer filtering performed on the input measurement sample data A;
B represents a measurement value obtained after the physical layer filtering;
Layer 3 filtering represents high layer filtering performed on the measurement value B;
C represents a measurement result obtained after the high layer filtering; and
D represents a measurement report.
For the network side, evaluation of reporting criteria represents a process for determining whether a high layer at the network side needs to perform a corresponding radio resource management (RRM) according to the measurement result C; and for the terminal side, evaluation of reporting criteria represents a process for determining whether the terminal side needs to send the measurement report D to the high layer at the network side.
Based on the model, a solution for processing the measurement sample data at the terminal side in the WCDMA system specifically includes the following steps.
In step a, the physical layer at the terminal side performs a measurement to obtain measurement sample data.
In step b, the physical layer at the terminal side performs physical layer filtering on the measurement sample data to obtain a measurement value, and provides the obtained measurement value to the high layer at the terminal side.
In step c, the high layer at the terminal side filters the received measurement value according to equation (1), and a measurement result is obtained.Fn=(1−a)·Fn−1+a·Mn  (1)
Here, Fn represents a measurement result obtained after the current filtering operation; Fn−1 represents a measurement result obtained after a previous filtering operation; Mn represents a measurement value currently received from the physical layer; n is a natural number; F0 is equal to the first measurement value M1 received from the physical layer; and a=½(k/2), where k is a filtering coefficient.
The operation specifically includes performing slide filtering on the current measurement value and the measurement result obtained after the previous operation. That is, the current measurement value and the measurement result obtained after the previous operation may be multiplied by a respective weighting coefficient and added to the results, so as to obtain a current measurement result. Here, the sum of the two weighting coefficients is 1.
In step d, according to each measurement result obtained after filtering, the high layer at the terminal side determines whether a measurement report sent to the high layer at the network side needs to be triggered, or whether other RRM processes need to be triggered.
For example, after determining that the obtained measurement result F3 exceeds a preset measurement value, the high layer at the terminal side may determine that the measurement report needs to be sent to the high layer at the network side.
For the network side, the process is similar to process described above, and the difference lies in that when performing the operation corresponding to step d, the high layer at the network side specifically determines whether a corresponding RRM process needs to be performed or not according to each measurement result obtained after filtering.
Through the above process, the measurement of a signal, including measurement of the quality of a pilot signal can be realized.
However, the inventor found that in the WCDMA system, the measurement frequency bands of all measurement sample data are the same, and the above measurement process is mainly directed to different measurement sample data in the time domain. However, in the LTE system, different measurement sample data corresponds to different carrier frequencies and bandwidths in a measurement frequency band. Apparently, in this case, if the existing Layer 3 filtering in the WCDMA system is adopted in the LTE system, time domain and frequency domain characteristics of the measurement sample data in LTE signals are not considered.
If the LTE system does not perform Layer 3 filtering on the measurement value, the system has to process more measurement sample data, which will result in unnecessary memory occupation and long measurement duration. Meanwhile, because there is no uniform and effective Layer 3 filtering method, different manufacturers may use different filtering methods, which will inevitably cause inconsistent measurement results, thus affecting the network performance.